TOKYO — Tons of contaminated groundwater from the stricken Fukushima Dai-ichi nuclear plant are emptying daily into the Pacific, creating what a top regulator called a crisis.
The water contains strontium — a particularly dangerous isotope if it gets into the food chain — as well as cesium and tritium, which are considered less dangerous when released into the ocean. The plant's operator says it does not yet pose a health threat because levels of the contaminants are still very low in the open ocean.
But regulators and critics alike worry because the company, Tokyo Electric Power Co., or Tepco, has been unable to stop the flow of the contaminated water, which appears to have started between December and May.
"Tepco lacks a sufficient sense of urgency for this crisis," Shinji Kinjo, a high-level official at the country's nuclear regulatory watchdog, said in an interview Tuesday.
The plant was already struggling to store hundreds of thousands of tons of contaminated water that flowed through the buildings housing three reactors that experienced meltdowns in 2011. But the contamination in this new groundwater problem is from different sources, Tepco said.
To halt the flow of contaminated water, Tepco built an underground barrier along the shoreline in front of one damaged reactor in June by injecting chemicals into the soil to harden it. But Tepco has told regulators that it believes that the barrier failed to stop the water, instead acting like a dam that pooled the contaminated underground water behind it until it flowed over the top of the barrier toward the sea.